1. Field of the Invention
The present invention relates to coil tubing units and to a method and apparatus for the running of various tools having hollow internal bores on a coil tubing unit where solid measuring wire-line equipment cannot adequately perform because of an accumulation of sand and/or debris, and/or the requirement of additional pulling capacity that is unavailable with a conventional wire-line.
2. General Background
There are various devices which are used to "service" an oil or gas well. These service applications can include the running or pulling of safety valves and gas lift valves, the running plugs in the well and setting them, washing sand and debris off wire-line tools, opening and closing sliding side doors, and cutting parafin. In some cases however, a solid "wire-line" can not be used to service a well because of the accumulation of debris or sand or the line does not have the strength of a coil tubing unit necessary to pull a given device from the well. Typical workover units or snubbing units which might approach a solution to the problem which the present invention solves are extremely expensive to operate.
The use of coil tubing units in general can be seen, for example, in U.S. Pat. No. 3,791,447 issued to Arthur Smith, et al. entitled "Well Methods for Sand Bridge Removal Using Small Diameter Tubing," and U.S. Pat. No. 3,722,594 issued to Arthur Smith, et al. entitled "Well Methods Using Small Diameter Tubing," incorporated herein by reference. Coil tubing units are commercially available and sold by a number of manufacturers such as, eg. by Hydra Rig, Incoporated of Fort Worth, Tex. A patent relating to the use of wire-line tools can be seen in the Daniel U.S. Pat. No. 3,401,749 entitled "Method and Apparatus for Moving Wire-line Tools Through Deviated Well Bores." Other possibly pertinent prior art considered with respect to this invention includes, for example, the following U.S. patents.
__________________________________________________________________________ U.S. Pat. No. Inventor Invention Issue Date __________________________________________________________________________ 3,554,284 Nystrom, H. "Methods for Facilitating 01/12/71 The Descent of Well Tools Through Deviated Well Bores" 4,082,144 Marquis, G. "Method and Apparatus for 04/04/78 Running and Retrieving Logging Instruments in Highly Deviated Well Bores" 3,727,693 Tausch et al. "Method and Fluid System 04/17/73 For Moving Subsurface Well Equipment in Well Tubing" 3,040,808 Schramm et al. "Method and Apparatus for 06/26/62 Perforating Oil Wells" 3,830,304 Cummins, A. "Wellhead Isolation Tool 08/20/74 and Method of Use Thereof" 3,658,126 Bohlmann, et al "Servicing Wells" 04/25/72 3,312,282 E. D. Yetman "Pumping Well Tools 04/04/67 Through Flowlines of Irregular Diameter" 3,363,880 L. Blagg "Cable-Feeding Apparatus" 01/16/68 3,401,749 W. L. Daniel "Method and Apparatus for 09/17/68 Moving Wire-Line Tools Through Deviated Well Bores" 3,675,718 Kanady, W. "Conducting Operations In 07/11/72 A Well Through A Normally Closed Valve" 2,810,442 Tausch, G. "Flexible Tubular Extension 10/22/57 Member for Wells" __________________________________________________________________________
The above patents relate generally to coil tubing units or to wire-line units or wire-line tools and do not solve the problem of running tools such as carrying tools, pulling tools, fishing tools, jars and the like with a coil tubing unit.
To solve this problem, and to satisfy the above described applications, a coil tubing unit with the pipe having an exemplary minimum line pull of 14,000 lbs. and a maximum of 20,000 lbs. can be used as specified herein with a special carrying tool to "run" hollowed tools with internal flow bores into the well. The coil tubing unit can thus perform several desirable functions such as: (1) wash debris and sand from the well to the "fishing neck" or "stuck" wire-line tools; (2) allow continuous circulation while jarring or pulling a particular wire-line apparatus; and (3) allow continuous circulation and thus equalized pressure when removing safety valves from the well (such as surface-controlled wire line retrievable tubing safety valves, as eg. OTIS model DS, DK, DR "STORM CHOKES"). In the removal of such safety valves that are "stuck" the coil tubing unit can provide much greater pulling capacity than a wire-line, saving the use of a more expensive workover rig or snubbing unit if the wire-line unit cannot retrieve the valve. If the wire-line cannot relieve such a "stuck" valve (or like tool), a snubbing unit or workover rig must be used to remove the "stuck" tool or valve. Fishing necks on such valves or tools can be grabbed with an off/on overshot or releaseable spear such as manufactured by Baker Oil Tools. These tools are hollowed with an internal bore to allow for circulation.
Other tools which can be pulled or run with the method and apparatus of the present invention include for example, jars, all runnings tools, all pulling tools. Applications using this method and apparatus include: (1) washing sand and debris off wire-line tools and fishing tools; (2) washing down to plugs and pulling them; (3) running plugs in the well and setting them; (4) opening and closing sliding side doors; (5) running and pulling chokes; (6) running and pulling gas lift valves; (7) cutting parafin; and (8) running and pulling safety valves.